438 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



promulgation of the new theory has not resulted in the 

 conversion of a single known breeder to the extent of 

 inducing him to conform his methods and practice to 

 the theory. My conclusion is that they are essentially 

 right in their deductions founded on their experience 

 and observations, namely, that acquired characters 

 may be, and sometimes are, transmitted, and that the 

 speculations of the Weismann school of naturalists are 

 unfounded." 



5 THE CONDITIONS OF INHERITANCE. 



Since the evidence adduced must be regarded as 

 proving that characters acquired by an organism may 

 be transmitted by inheritance, we next endeavor to 

 ascertain what information is within our reach which 

 can throw light on this mysterious process. Although 

 Weismann has demonstrated the isolation and stability 

 of the germ-plasma to exceed that of other tissues, he 

 has not proven that it is entirely inaccessible to exter- 

 nal influences. He admits that its continual subdivi- 

 sion by the development from it of the embryonic 

 soma, would have speedily reduced it to an infinitesi- 

 mal quantity, were it not that it grows by accession of 

 nutritive material like other tissues, which nutritive 

 material is furnished by the soma. The accessibility 

 of the germ-plasma to stimuli which affect the soma is 

 then clearly possible. 



The effect of the specialization of tissues on their 

 nutrition and repair after injury, is well known. Nu- 

 trition of each tissue produces only that tissue. Re- 

 pair or restoration of parts is confined to the repro- 

 duction of a tissue similar to the part lost, or similar 

 to some unfinished or embryonic stage of it. The 

 lower we descend in the scale of life, the more com- 



